San Anselmo, CA 94903 Frost Dates
San Anselmo, CA: when does the frost end?
Typically, the last spring freeze lands around 01/11, roughly 136 days out. Fall's first freeze usually shows up around 12/21, roughly 349 days after the last spring frost.
Zone 9b (25 to 30°F average annual minimum) comes from the USDA Plant Hardiness Zone Map; the frost dates above are the 1991-2020 normal at the nearest reporting NOAA station for San Anselmo, not a forecast for this year.
Stretching the season past the first frost
With roughly 16 weeks until San Anselmo's first fall frost, a row cover or cold frame is what stretches the last few weeks of harvest here.
How much risk comes with planting early here
01/11 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 02/25 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 12/14 and only about 1 year in 10 sees frost after that.
San Anselmo against the rest of the dataset
About 349 days separate San Anselmo's last and first frost, putting it 2,343 of 40,283 ZIP codes nationally. Within CA, it ranks 1,049 of 2,555.
Learn more
Before leaning on 94903's figures: the frost range explains how to read the range around San Anselmo's dates instead of trusting one, while local microclimates explains what one yard in San Anselmo can differ from the 94903 normal.